10 Times The Simpsons Broke Its Own Rules
3. The Simpson Gene
At the end of Lisa The Simpson from Season 9, the middle Simpson child is cured of her fears of losing her intelligence after she finds out the so-called "Simpson Gene" only affects males.
The Simpson Gene, as described by Grampa, causes members of the family to grow dumber as they grow older. However, as proven when Homer tracks down extended members of the clan, it is only those with a Y Chromosome who lose their smarts.
However, there are two glaring exceptions.
One is Homer's half-brother, Herb Powell. He's a Simpson by birth, but displays fantastic intelligence in the two episodes we see him. He's the head of his own company and even invents a device that lets adults communicate with babies! Doesn't get much smarter than that!
The other outlier? Lisa's own father.
In the episode HOMR, it is revealed that Homer is so stupid because he had a crayon lodged in his brain. After the offending item is removed, he becomes super intelligent. Miserable, but intelligent.
It's clear then that the Simpson Gene does not affect all of the Simpson men. Then again, we did hear about the Gene from Grampa, so maybe we're the stupid ones after all.